The Western Hoolock Gibbon: India’s Only Ape

India has exactly one ape species. Not a monkey, not a langur — a true ape, in the same broad family as gorillas and chimpanzees, just far smaller. It lives only in the country’s northeast.

A male Western Hoolock Gibbon, Hoollongapar Gibbon Sanctuary, Jorhat, Assam. Photo by Kumud Ghosh, CC BY 4.0, via Wikimedia Commons.

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EnvEco0054 · Environment and Ecology

The Western Hoolock Gibbon

From an ancient species split to a shrinking population in Northeast India

2005

Split From Eastern Hoolock Recognised

Formally recognised as a separate species from the Eastern Hoolock Gibbon (H. leuconedys). The two lineages had actually diverged around 1.49 million years ago, on either side of the Chindwin River in Myanmar.

Habitat

Hoollongapar Gibbon Wildlife Sanctuary

In Jorhat district, Assam — India’s only sanctuary dedicated specifically to gibbons. The species survives in pockets of Northeast India, roughly east of the Brahmaputra and Dibang rivers.

IUCN Red List

Endangered

The population has collapsed from roughly 100,000 decades ago to under 5,000 today — driven by habitat loss to tea gardens, rubber plantations, and jhum cultivation, plus hunting.

2021

Genetic Study Confirms India’s Single Species

A genetic study confirms only the Western Hoolock Gibbon actually lives in India. Earlier reports of the Eastern Hoolock in Arunachal Pradesh and Assam turn out to be mistaken.

An Ape, Not a Monkey

Macaques and langurs also live in Northeast India, but they are monkeys, not apes. The tailless, long-armed Western Hoolock Gibbon is India’s only true ape — a specialised brachiator that swings hand-over-hand through the canopy instead of running along branches.

📑 Contents

1India’s Only Ape
2Life in the Canopy
3Test Yourself
4Threats and a Genetic Surprise

India’s Only Ape Need to Know

The Western Hoolock Gibbon (Hoolock hoolock) is India’s only ape species. Macaques and langurs are monkeys, not apes.
It lives across Northeast India, roughly east of the Brahmaputra and Dibang rivers, including Assam, Meghalaya, and Nagaland.
It is listed as Endangered on the IUCN Red List. Its population has collapsed from roughly 100,000 decades ago to under 5,000 today.
The Hoollongapar Gibbon Wildlife Sanctuary, in Jorhat district, Assam, is India’s only sanctuary dedicated specifically to gibbons.
They are small, lightweight apes, around 6–9 kg — nothing like the heavy build of a gorilla.

Life in the Canopy Good to Know

They are specialised brachiators. Long, slender forelimbs let them swing rapidly between trees, among the fastest tree-travelling primates alive.
Adult males are uniformly black, with a prominent white brow band. Adult females are buff or golden-grey, often with darker patches on the head and chest.
Infants of both sexes are born pale. Males darken to black around six months old, while females keep their lighter colour through puberty.
They live in small, monogamous family groups, typically four to six members, made up of a mated pair and their offspring.
Pairs perform loud duet “songs” from the canopy, for territorial defence and to signal their bond. Unusually for gibbons, males join the duet’s loudest “great call” section too, not just females.
Their diet is mostly fruit, especially figs, drawn from more than 76 plant species. They also eat leaves, shoots, flowers, insects, and occasionally bird eggs when fruit is scarce.

Test Yourself

Threats and a Genetic Surprise Great to Know

Habitat loss is the biggest threat. Northeast India’s forests have given way to tea gardens, rubber plantations, jhum (shifting) cultivation, and new infrastructure corridors.
In Assam specifically, gibbon populations often end up isolated in small forest patches, surrounded by tea estates. That fragmentation limits their access to food and mates.
Hunting adds further pressure in parts of the region.
The Western Hoolock Gibbon split from its close relative, the Eastern Hoolock Gibbon, around 1.49 million years ago, on either side of the Chindwin River in Myanmar. The two were only formally recognised as separate species in 2005.
A 2021 genetic study settled a real taxonomic question. It confirmed only the Western Hoolock Gibbon actually lives in India — earlier reports of the Eastern Hoolock in parts of Arunachal Pradesh and Assam turned out to be mistaken.

The Statements, and the Answer Key

The sanctuary and IUCN-Endangered claims are both genuinely correct, and so is the brachiation claim.
The trap is the gorilla comparison. A heavy, gorilla-like build would work against, not support, the agile tree-climbing these gibbons are known for.